As an application field of Thin Film Transistor Liquid Crystal Display (TFT-LCD) becomes much broader, technologies like a large scale LCD, a large aperture opening ratio LCD and Gate Driver on Array (GOA) develop greatly. However, a display panel with the large scale and large aperture opening ratio as stated above also has a problem regarding picture quality.
In order to improve the quality of pictures, it is generally needed to compensate common electrodes. FIG. 1 shows a structural diagram of a display panel implementing the common electrode compensation conventionally. A common electrode bus 01 is arranged peripherally around a display area 00 on the display panel of TFT-LCD to implement common electrode connections on the display panel. Source driver circuits 02 (also referred to as a source driver IC) are provided outside a top portion of the common electrode bus 01. Gate driver circuits are provided outside both side of the common electrode bus 01. Because gate drivers are usually manufactured using the GOA technology, GOA circuits 03 are provided on both sides of the display area 00. On the outside of the GOA circuits 03, a feedback signal line is provided, which is connected to the common electrode bus 01 to input a feedback voltage to the common voltage driving compensation units 05. The common voltage driving compensation units 05 are used to compensate the source driver circuits. FIG. 2 shows a principle diagram of a common voltage driving compensation unit 05, in which the common voltage driving compensation unit 05 includes an operational amplifier, an in-phase input terminal 051 at which a common electrode voltage is inputted, a reverse-phase input terminal 052 at which a feedback voltage provided by the feedback signal line is inputted, and an output terminal 053 at which a compensated common electrode voltage is outputted.
As for a display panel with a heavy-load, a common electrode compensation (i.e. Vcom compensation) with a higher amplification ratio is used in general. However, uniform compensation on the whole display panel can't be achieved with the conventional Vcom compensation manners, and a reddish phenomenon is caused on the display panel at an end near to the source driver circuit (i.e. a near end) due to over-compensation. In contrast, at an end far from the source driver circuit (i.e. a far end), a greenish phenomenon is caused on the display panel due to under-compensation, and thus a picture quality is degraded.